An electronic device is a device that performs a specific function according to a program provided therein, such as an electronic scheduler, a portable multimedia reproducer, a mobile communication terminal, a tablet PC, an image/sound device, a desktop/laptop PC, or a vehicular navigation system, including a home appliance. For example, such an electronic device may output information stored therein as sound or an image. In addition, portable electronic devices, such as a laptop computer, a tablet PC, an electronic scheduler, a portable multimedia player, and a mobile communication terminal, are generally equipped with a display device and a battery. Portable electronic devices, such as an electronic scheduler, a portable multimedia reproducer, a mobile communication terminal, and a tablet PC, are generally equipped with a display device and a battery, and have a bar-type, folder-type, or sliding-type appearance.